Highly absorbent polyester fibers

Abstract

A hollow polyester filament is disclosed that has sufficient openings therein for the hollow filament to substantially fill with water. The polyester filament has a moisture absorption capability of between about 10 and 30 percent by volume.

1 . A hollow filament having sufficient openings therein for said hollow filament to substantially fill with liquid.  
     
     
         2 . A hollow polyester filament having sufficient openings therein for said hollow filament to substantially fill with a liquid selected from the group consisting of water, water-based solutions, and water-based suspensions.  
     
     
         3 . A hollow filament according to  claim 1  consisting essentially of polyethylene terephthalate.  
     
     
         4 . A staple fiber cut from the hollow filament of  claim 1 .  
     
     
         5 . A staple fiber according to  claim 4  and having a length sufficient to exhibit fiber properties.  
     
     
         6 . A staple fiber according to  claim 4  and having a length sufficient to support meniscus of water at each end thereof.  
     
     
         7 . A staple fiber according to  claim 4  having a length of between about one-quarter inch and two inches.  
     
     
         8 . A nonwoven fabric formed from a plurality of staple fibers according to  claim 4 .  
     
     
         9 . A nonwoven fabric formed from a plurality of staple fibers according to  claim 7 .  
     
     
         10 . An absorbent structure that includes a nonwoven fabric according to  claim 9 .  
     
     
         11 . A hollow filament according to  claim 1  wherein both said filament and its hollow portion have respective circular cross section.  
     
     
         12 . A hollow filament according to  claim 1  wherein said filament has a circular cross section and said hollow portion has a non-circular cross section.  
     
     
         13 . A hollow filament according to  claim 1  wherein said filament has a non-circular cross section and said hollow portion has a circular cross section.  
     
     
         14 . A hollow filament according to  claim 1  wherein said filament has a non-circular cross section and said hollow portion has a non-circular cross section.  
     
     
         15 . A hollow staple fiber consisting essentially of polyethylene terephthalate and having sufficient openings therein for said staple fiber to substantially fill with water.  
     
     
         16 . A polyester filament having a moisture absorption capability of between about 10 and 30 percent by volume.  
     
     
         17 . A filament according to  claim 16  consisting essentially of polyethylene terephthalate.  
     
     
         18 . A hollow filament according to  claim 16 .  
     
     
         19 . A hollow filament according to  claim 16  wherein both said filament and it s hollow portion have respective circular cross section.  
     
     
         20 . A staple fiber cut from the filament of  claim 16 .  
     
     
         21 . A nonwoven fabric formed from the staple fiber of  claim 20 .  
     
     
         22 . An absorbent structure that includes a nonwoven fabric according to  claim 21 .  
     
     
         23 . A hollow filament according to  claim 18  and having an asymmetric cross section.  
     
     
         24 . A hollow filament according to  claim 23  wherein both said filament and it s hollow portion have respective circular cross section and said hollow portion is not coaxial with said filament.  
     
     
         25 . A staple fiber cut from the filament of  claim 23 .  
     
     
         26 . A nonwoven fabric formed from the staple fiber of  claim 25 .  
     
     
         27 . An absorbent structure that includes a nonwoven fabric according to  claim 26 .  
     
     
         28 . A staple fiber consisting essentially of polyethylene terephthalate and having a moisture absorption capability of between about 10 and 30 percent by volume.  
     
     
         29 . A hollow filament having an asymmetric cross section and having sufficient openings therein for said hollow filament to substantially fill with liquid.  
     
     
         30 . A hollow polyester filament having an asymmetric cross section and having sufficient openings therein for said hollow filament to substantially fill with a liquid selected from the group consisting of water, water-based solutions, and water-based suspensions.  
     
     
         31 . A filament according to  claim 29  consisting essentially of polyethylene terephthalate.  
     
     
         32 . A filament according to  claim 29  wherein both said filament and its hollow portion have respective circular cross sections and wherein said hollow portion is not coaxial with said filament.  
     
     
         33 . A staple fiber cut from the filament of  claim 29 .  
     
     
         34 . A staple fiber according to  claim 33  having a length of between about one-quarter inch and two inches.  
     
     
         35 . A nonwoven fabric formed from a plurality of staple fibers according to  claim 34 .  
     
     
         36 . An absorbent structure that includes a nonwoven fabric according to  claim 35 .  
     
     
         37 . A hollow staple fiber consisting essentially of polyethylene terephthalate; 
 said staple fiber having sufficient openings therein for said staple fiber to substantially fill with a liquid; and    said staple fiber and its hollow portion having respective circular cross sections and wherein said hollow portion is not coaxial with said staple fiber.    
     
     
         38 . A hollow staple fiber according to  claim 37  having sufficient openings therein for said staple fiber to substantially fill with a liquid selected from the group consisting of water, water-based solutions, and water-based suspensions.  
     
     
         39 . A method of forming a highly water-absorbent polyester filament, the method comprising: 
 contacting a hollow polyester filament with a chemical composition in an amount and for a time sufficient to attack the hollow filament and create sufficient openings therein for the hollow filament to substantially fill with a liquid while less than an amount that would completely open or dissolve the filament.    
     
     
         40 . A method according to  claim 39  comprising creating sufficient openings for the hollow filament to substantially fill with a liquid selected from the group consisting of water, water-based solutions, and water-based suspensions.  
     
     
         41 . A method according to  claim 39  comprising contacting the filament with an aqueous alkali solution.  
     
     
         42 . A method according to  claim 41  comprising contacting the filament with the aqueous alkali solution at an elevated temperature.  
     
     
         43 . A method according to  claim 41  comprising contacting the filament with an aqueous solution selected from the group consisting of sodium hydroxide, potassium hydroxide and ammonium hydroxide.  
     
     
         44 . A method according to  claim 39  comprising contacting the filament with an organic solvent for polyester.  
     
     
         45 . A method according to  claim 39  comprising contacting the filament with a solvent selected from the group consisting of: benzene, esters and ketones.  
     
     
         46 . A method according to  claim 39  comprising contacting the filament with a plasticizer.  
     
     
         47 . A method according to  claim 39  comprising contacting a polyethylene terephthalate filament.  
     
     
         48 . A method according to  claim 39  and further comprising the step(s) of spinning the hollow filament from a melt prior to the step of contacting the filament with the attacking composition.  
     
     
         49 . A method according to  claim 48  comprising spinning a hollow filament with an asymmetric cross section.  
     
     
         50 . A method according to  claim 39  and further comprising cutting the filament into staple fibers.  
     
     
         51 . A method according to  claim 50  and further comprising forming a nonwoven fabric from the cut staple fibers.  
     
     
         52 . A method according to  claim 41  and further comprising neutralizing the filament after contacting the filament with the aqueous alkali solution.  
     
     
         53 . A method according to  claim 39  and further comprising the steps of: 
 heat setting the filament;  
 cutting the filament into staple fibers; and  
 baling the cut staple fibers;  
 all following the step of contacting the filament with the chemical composition.  
 
     
     
         54 . A method of forming a highly absorbent synthetic polymer filament, the method comprising: 
 contacting a hollow polymeric filament with an organic solvent for the polymer in an amount and for a time sufficient to attack the hollow filament and create sufficient openings therein for the hollow filament to substantially fill with a liquid while less than an amount that would completely open or dissolve the filament.    
     
     
         55 . A method according to  claim 54  comprising creating sufficient openings for the hollow filament to substantially fill with a liquid selected from the group consisting of water, water-based solutions, and water-based suspensions  
     
     
         56 . A method according to  claim 54  comprising contacting a hollow polyester filament with the solvent.  
     
     
         57 . A method of forming a highly absorbent synthetic polymer filament, the method comprising: 
 mechanically cracking a hollow polymeric filament until the filament is sufficiently open to substantially fill with a liquid.    
     
     
         58 . A method according to  claim 57  comprising mechanically cracking a hollow polyester filament until the filament is sufficiently open to substantially fill with a liquid selected from the group consisting of water, water-based solutions, and water-based suspensions.  
     
     
         59 . A method according to  claim 57  comprising cracking a filament that has a asymmetric cross section.  
     
     
         60 . A method according to  claim 59  and further comprising the step of spinning the asymmetric filament from a melt prior to the step of mechanically cracking the filament.  
     
     
         60 . A method according to  claim 59  and further comprising the step of spinning the asymmetric filament from a melt prior to the step of mechanically cracking the filament.  
     
     
         61 . A method according to  claim 59  and further comprising cutting the filament into staple fiber.  
     
     
         62 . A method according to  claim 61  and further comprising forming a nonwoven fabric from the staple fibers.  
     
     
         63 . A method according to  claim 59  and further comprising the step of spinning the asymmetric filament prior to the step of mechanically cracking the filament.  
     
     
         64 . A method according to  claim 57  and further comprising spinning the hollow filament from a melt prior to the step of cracking the filament.  
     
     
         65 . A method according to  claim 64  and further comprising cutting the filament into staple fiber.  
     
     
         66 . A method according to  claim 65  and further comprising forming a nonwoven fabric from the staple fibers.  
     
     
         67 . A method according to  claim 57  comprising cracking a filament consisting essentially of polyethylene terephthalate.  
     
     
         68 . A method according to  claim 57  and further comprising the steps of heat stting the filaments; 
 cutting the filaments into staple fiber; and  
 baling the cut staple fibers.  
 
     
     
         69 . A method of forming a highly absorbent polyester filament, the method comprising: 
 spinning an asymmetric hollow filament from a melt;    preferentially quenching the filament to create greater and lesser degrees of    polymer orientation along the filament;    drawing the filament to a desired draw ratio;    heat setting the drawn filament; and    mechanically cracking a hollow polyester filament until the filament is sufficiently open to substantially fill with a liquid.    
     
     
         70 . A method according to  claim 69  comprising mechanically cracking the filament until the filament is sufficiently open to substantially fill with a liquid selected from the group consisting of water, water-based solutions, and water-based suspensions.  
     
     
         71 . A method according to  claim 69  wherein the drawing step comprises drawing the filament to degree that highly stresses the more highly oriented portions of the filament.  
     
     
         72 . A staple filament having a coaxial opening entirely therethrough, the filament having a length defined by the minimum length sufficient to support a meniscus of water in the coaxial opening and a maximum length at which the filament will fill entirely with a liquid selected from the group consisting of water and water-based solutions and suspensions.  
     
     
         73 . A staple filament according to  claim 72  wherein the maximum length is the length above which air pressure between a meniscus at each end of the filament will prevent the opening from filling entirely with the selected liquid.  
     
     
         74 . A staple filament according to  claim 72  comprising polyester.  
     
     
         75 . A staple filament according to  claim 72  comprising polyethylene terephthalate.  
     
     
         76 . A staple filament according to  claim 72  having a length less than about one-half inch.  
     
     
         77 . A staple filament according to  claim 72  having a length of about one-quarter inch.  
     
     
         78 . A staple filament according to  claim 72  having a denier of between about 1 and 45.  
     
     
         79 . A staple filament according to  claim 72  having a denier of between about 1 and 10.  
     
     
         80 . A staple filament according to  claim 72  having a denier of between about 1 and 3.  
     
     
         81 . A method of forming a highly absorbent filament comprising: 
 spinning a hollow filament at a denier of between about 1 and 45;    quenching the filament; and    cutting the filament into short staple fibers having a length defined by the minimum length sufficient to support a meniscus of water in the coaxial opening and a maximum length at which the filament will fill entirely with a liquid selected from the group consisting of water and water-based solutions and suspensions.    
     
     
         82 . A method according to  claim 81  comprising spinning a polyester hollow filament.  
     
     
         83 . A method according to  claim 81  comprising spinning the filament to a denier of between about 1 and 10.  
     
     
         84 . A method according to  claim 81  comprising spinning the filament to a denier of between about 1 and 3.  
     
     
         85 . A method according to  claim 81  comprising cutting the filament into staple less than about one-half inch in length.  
     
     
         86 . A method according to  claim 81  comprising cutting the filament into staple about one-quarter inch in length.